Weekly Report 2 09/30/2016
This week we continued our search for existing protocols that might be of values to us. A specialized myocardial temperature sensor from both Smiths-medical and NOVATEMP caught our attention. Both of the two separate companies employ the same design of a penetrating needle positioned at right angle with signal transmission cable with an ultrathin sensor placed at distal tip which provides accurate, on-site temperature readings. Here, they use the most straightforward way---physical penetrating, to get through the lipid layer enveloping the myocardium. Such invasive"procedure will inevitably leave a hole on the heart surface and we think of it as something we should avoid. That being said, the thermocouple sensor of this design achieve a reliable accuracy of 0.2℃ across the common surgical temperature range(25℃~50℃). So we are considering using the same thermocouple sensor MTS-TC8 manufacured by Level1, at a labeled price of 500 dollars. We are going to look for if there is any cheaper option during the coming week.
Weekly Report 3 10/07/2016
This week, our group has been working on writing the preliminary report for the class. On Monday and Tuesday, we met together to explore all the existing solutions on the market for temperature monitoring, and discussed about their individual advantages and drawbacks since we have to make our design an unique and better solution for the problem. On the following days of the week, we’ve been finalizing our design scope and try to ask for help from instructors to set a specific design plan. After choosing wifi transmission on sensor as our main plan, we just got together, and finished our preliminary report.
Weekly Report 4 10/14/2016
This week we listened to a lot of great student presentations on their projects and we got insight into our project as well. We did more research on how to achieve the wireless function as we proposed in the report and the presentation. One of the options that we looked into is the radio-frequency identification (RFID), which uses electromagnetic fields to automatically identify and track tags attached to objects. The tags contain electronically stored information. There are passive and active tags. Passive tags collect energy from a nearby RFID reader's interrogating radio waves. Active tags have a local power source such as a battery and may operate at hundreds of meters from the RFID reader. We will probably choose this method because RFID is FDA approved, while we have concerns over other wireless connecting options that would potentially not pass FDA regulations.
Weekly Report 5 10/21/2016
This week we only had three days after we came back from fall break. We did a brief research on our temperature sensor. There are 7 types of thermocouples available. Type K is the most commonly used one because of it offers acceptable reliability, accuracy and wide temperature range at a low cost. The last feature might appeal to us because we have limited budget. However, the reported error could go up to 2.2 degrees, which is kind of crude. Another option best suited for our purpose would be type T. It is more stable and more accurate in lower temperature range and is often used in cryogenics, which happens to be one of the alternatives to maze ablation. We are currently thinking of going for type K to control the cost. However, we also reserve the option of type T in case the final product yields unsatisfying accuracy.
Weekly Report 6 10/28/2016
This week, we worked on our website, http://myocardial-temperature-monitor.weebly.com/. We also focused on our scinote, making sure us writing down all the things we did over the past few weeks. We also performed an experiment regarding the needle shape we are going to use for our design. Although we found that spiral shaped needle would be the most stable option, it might cause too much damage on the heart muscle during the procedure. Hence, we decide to design a hook-shaped needle.
Weekly Report 7 11/4/2016
This week we did more research and design for the wireless feature of our product. A RFID system consists of two components, a tag and a reader. The tag must be attached to the temperature probe. After researching the various products available in the market, we found several suitable options. The first one is UHF 860-960 MHz Mini Mount-on Metal RFID Tag. With a size of 0.5 in x 0.4 in x 0.11 in, it is almost similar to the size of a paper clip. Because this tag is designed to be mounted on metal, we could mount it onto our temperature sensor, which would probably be made of metal. The other option is a UHF 860-960 MHz Temperature Sensing RFID Tag. This tag incorporates temperature-sensing feature with a ±0.1 °C accuracy. Its operating temperature range is -30 °C to 70 °C. The dimension is 130.4 mm x 23.4 mm x 12.7 mm. All parameters are suitable with our design. Moreover, the tag can be programmed to set a specific temperature threshold. Once the temperature drops or exceeds the threshold, it would trigger an alert.
Weekly Report 8 11/11/2016
Continuing our discussion on the wireless feature from last week, we proceeded to pick A/D converters for analog to digital signal conversion. First, we turned to the renowned manufacturer of electronic devices Texas Instrument. It lives up to its reputation. TI offers high speed ADC products(>10MSPS) encompassing an entire range of resolution, power consumption and signal-to-noise ratio(SNR) to cater for different purposes. In our case, we are measuring the temperature from a thermocouple sensor and sampling the voltage output into digital signal. Temperature variation in a surgery, ideally, should be relatively moderate and stable. Thus even the lower end of the product line that offers 12~10 bits resolution would be sufficient for our purpose. Most of the TI ADC also achieve a SNR over 70dB. Again, this should be enough to eliminate the power line noise in the surgery room. Their power consumption are all well below 2W, with over half of them costing merely several hundreds milliwalts. Our cell battery could easily afford that for the span of even a longlasting surgery. The only uncertain factor is the output/input voltage range. We still have not experimented with the thermocouples. We will determine which ADC to purchase after ensuring it falls into the sensor output range. Overall, TI is a very cost-effective choice and most likely we are purchasing from them. Other suppliers either cannot beat TI’s price or unable to offer products with as satisfying parameters.
Weekly Report 9 11/18/2016
This week, we further explored the options of the thermometer needle head. We thought more about the design alternatives rather than the simple, straight and stiff needle, and the possible ways of measuring it. We also discussed their individual advantages and drawbacks. Our plan now is to get order the thermistor online, and explore the option of making a hard, retractable cover that can penetrate the surface of the heart, and then, once reach the desired area of interest, expose the thermistor’s head, and measure the temperature there. In addition, we also did the QPSK/BPSK experiment to try to encode for data.
Weekly Report 10 12/2/2016
This week we have been primarily working on our progress report. To meet the criteria for the progress report, we did further search on the budget requirement part. Cost for individual parts of the design was found, and our final budget request is 150 dollars.
Weekly Report 11 1/27/2017
After returning to school, we have been straightening out what we already have on hand and fit the rest of our project neatly into the limited timeframe of three months. As we start to build real protocols for the temperature monitor, purchase of equipment or electronics becomes the first urgency. We are operating on a limited budget around 200 dollars. But fortunately the microprocessor for wireless network and the thermal sensors are both readily affordable. So we are thinking about purchasing several alternatives along with the best choice determined by Pugh analysis last semester in case anything goes wrong. We are looking to buy a ZigBee and a Bluetooth module, $30 each. As for the thermistor costs around $40 or so. Hopefully the products shall arrive next week and we will begin the design work soon.
Weekly Report 12 2/3/2017
This week we worked on incorporating the temperature sensor with the needle and wireless component of our myocardial temperature sensor. We searched on the marketplace for parts that we need to purchase and prepared for money request to send to the department for building our first prototype. As we have decided in the last semester, thermocouple seems to be the best alternative for our myocardial temperature sensor, given its range of detection and sensitivity requirements. We finalized the option sold on Omega’s website. $45 with a dimension of 12 inches long, and 1/16 inch diameter. We also decided on a 22-gauge needle, the type of needle that is most popular in the market. We are planning on buying from Amazon, which is $5.99 for 10 packs. We also decided to pick 36-gauge lead wire, which provides accurate temperature readings by reducing the potential for ambient air to affect temperature monitoring.
Weekly Report 13 2/10/2017
This week, our group mainly came together and tried to learn more about implementing the Bluetooth functionality with Arduino and computer. Fortunately, we are able to find many examples and tutorials on using the microcontrol BT Arduino board, and the whole process, though still difficult, seems doable to us. Next step now, is to order the separate parts of Bluetooth Arduino, and try to assemble them together. However, we still has to learn how to implement the temperature sensing thermistor into the board.
Weekly Report 14 2/17/2017
This week we took the tool kits we have on hand to Professor Morley. He was the instructor for signal processing lab last semester and one of our team members took with him. We asked for his advice on our wireless configuration. He suggested that we use Bluetooth on Arduino and look up for similar Bluetooth code on the convenient database of Arduino. He also reminded us to check for the ISM band in which the transmission is being carried out and check if any other device in the operating suite might possibly fall in this same area and thus cause interference. We went on to check the frequency band in operating suite. It seems like surgical lights, monitors and anesthesia machines are all well out of this 2.4~2.485GHz range. So we can safely proceed to Bluetooth configuration.
Weekly Report 15 2/24/2017
This week we had two meetings. In our first meeting, we talked about the report that is due in one week. We made an outline for the content that we want to include in the report, and divided up the responsibility. In our second meeting, we placed order for all the materials that we need from online. We bought the thermistor and Bluetooth components according to our former plans. The components will arrive by the end of this week and we will work over the weekend to get the prototype working.
Weekly Report 16 3/3/2017
This week, we have been mainly working on our verification and validation report. Majority of time was spent on discussing how to verify the accuracy and range of thermistor. We cannot really find a constant temperature that will always remain in the same temperature with a difference of 2 degrees Celsius except for ice surface and boiling water. Hence, to test the accuracy of the thermistor, we will use these two as the standard temperatures. Although 0 and 100 are outside of our desirable temperature range, we believe that as the thermistor should have a much wider range, usually spanning 500 degrees Celsius, 0 and 100 degrees Celsius would be reasonable for checking the accuracy.
Weekly Report 17 3/10/2017
This week we mainly facilitated our group member Bicong in preparing her Validation& Verification presentation. This presentation also helped us organize what we have up to now and cleared up the way ahead. Our needle head finally came in on Wednesday. We luckily found that the hollowed needle head is of the exact appropriate size for the thermistor probe to insert in without falling out. We decide to prototype the temperature probe part of our device after spring break. Also our TA Nathan kindly offers to hold a help session on Bluetooth configuration, which would be tremendously helpful to us as we find it hard to get the Bluetooth to work on ourselves. We will make good use of it.
Weekly Report 19 3/31/2017
This past week we worked on integrating the thermistor with the needle head. In our design specifications, we planned to have three different lengths of needle to suit patients with different composition of body fat. For patients that have higher body fat, we prepared them with longer needles. We purchased three kinds of needles with varying diameters and two kinds of thermistors. It turned out that we can only use the glass encapsulated thermistors because if the two wires touch one another, it will cause fluctuations in the measurements. The glass encapsulated thermistors are slightly wider than the non encapsulated ones, and we eventually decided to use the middle-size needle head so that it’s neither too small or so large that the thermistor would easily fall off. Then we sealed the top of the needle head with glue gun. On the other hand, because we need to meet the specs of easily moving around the needle similar to the operation maneuvers. So we soldered the end of the two thermistor legs to two long wires, connecting to the Arduino boards.
Weekly Report 21 4/14/2017
For these two weeks, our group has been mainly focusing on developing our wireless Bluetooth Arduino module. Combining some of the online tutorial, the Bluetooth functionality seems to work as well as expected as the Arduino board sends out the signal via Bluetooth, and display devices like Iphone and MacBook can successfully receive the thermistor reading. Now, we are trying to change the original coding provided in the app online, and try to implement of functionalities. First, we need to scale our thermistor reading from resistance to temperature. Then, we need to include the adjustable temperature range function and implement the alarm feature in the app. So far we have been trying to alter the code using Swift, however, we might need to ask for help with regard to the coding process.
Weekly Report 22 4/21/2017
After seven months of hard efforts, this week, we happily announce that our product has come into fullform. We spent three sleepless nights debugging and fixing the Bluetooth code. Now the needle transmits temperature data from the thermistor robustly, and the receiving end displays the data accurately with four significant figures. We have fulfilled all of our design specifications. To wrap up thislong journey, we looked up for intellectual property issues. Though our product is qualified as a patent,we decide not to because we want others who are interested in our product make improvements based on our open-sourced code. It is not of immediate business value by now. We also did a video demonstration of our working product and prepared the final presentation next week. Without saying,we spent a lot of time editing our final report, too. We cannot believe that we come to an end. But we guess this is it. Farewell, Senior Design!